Metal gasket with independent and eccentric support bead

Abstract

A metal gasket for an internal combustion engine is installed between two engine parts. The metal gasket is formed of at least one metal plate extending substantially throughout an entire area of the engine to be sealed. The metal plate includes at least one bolt hole, a fluid hole situated near the bolt hole, a sealing device for surrounding the fluid hole to seal therearound, and a support bead situated around the sealing device without surrounding the bolt hole. The support bead is deviated from the fluid hole to balance surface pressure around the fluid hole when the engine parts are tightened. In case the gasket is formed of a plurality of metal plates, the sealing device and the support bead are formed on the different plates.

What is claimed is: 
     
       1. A metal gasket for an internal combustion engine to be installed between two engine parts, comprising: a metal plate extending substantially throughout an entire area of the engine to be sealed for constituting the metal gasket, said metal plate including at least one bolt hole for allowing a bolt to pass therethrough, a fluid hole situated near the bolt hole, sealing means surrounding the fluid hole to seal therearound, and a support bead situated around the sealing means without surrounding the bolt hole, said support bead being formed independently and separately from the sealing means and arranged to be deviated eccentrically from the fluid hole and the sealing means to provide substantially equal surface pressure on the sealing means around the fluid hole when the engine parts are tightened by the bolt passing through the bolt hole.   
     
     
       2. A metal gasket according to claim 1, wherein said support bead has longitudinal side portions and lateral side portions, a length between the longitudinal side portions being greater than a length between the lateral side portions and being oriented generally in a direction away from the bolt hole. 
     
     
       3. A metal gasket according to claim 2, wherein said support bead is arranged relative to the sealing means such that one of the longitudinal side portions is situated close to the sealing means to form a close portion of the bead relative to the sealing means. 
     
     
       4. A metal gasket according to claim 3, wherein the metal gasket is a cylinder head gasket situated under a cylinder head with a rigidity, said close portion being located near the bolt hole when the rigidity is high where the cylinder head does not substantially bend when the engine is tightened. 
     
     
       5. A metal gasket according to claim 4, wherein a surface pressure of the bead formed at the close portion is higher than a surface pressure formed at the longitudinal side portion opposite to the close portion. 
     
     
       6. A metal gasket according to claim 5, wherein the bead at the close portion has a width shorter than a width at the portion opposite to the close portion. 
     
     
       7. A metal gasket according to claim 4, wherein said sealing means is a bead concentrically surrounding the fluid hole. 
     
     
       8. A metal gasket according to claim 3, wherein said metal plate further includes an auxiliary bead situated in a space between the sealing means and one of the longitudinal side portions situated at a side opposite to the close portion. 
     
     
       9. A metal laminate gasket for an internal combustion engine to be installed between two engine parts, comprising: a first and second metal plates for constituting the metal laminate gasket, each of said first and second metal plates including at least one bolt hole for allowing a bolt to pass therethrough, and a fluid hole situated near the bolt hole,   sealing means surrounding the fluid hole to seal therearound, said sealing means being formed on one of the first and second metal plates, and   a support bead situated around the sealing means without surrounding the bolt hole, said support bead being formed on the other of the first and second metal plates independently and separately from the sealing means and being arranged to be deviated eccentrically from the fluid hole and the sealing means to provide substantially equal surface pressure on the sealing means around the fluid hole when the engine parts are tightened by the bolt passing through the bolt holes.   
     
     
       10. A metal laminate gasket according to claim 9, wherein said support bead has longitudinal side portions and lateral side portions, a length between the longitudinal side portions being greater than a length between the lateral side portions and being oriented generally in a direction away from the bolt hole of the plate where the support bead is formed. 
     
     
       11. A metal laminate gasket according to claim 10, wherein said sealing means is a sealing bead concentrically surrounding the fluid hole, and said support bead is arranged relative to the sealing bead such that one of the longitudinal side portions is situated close to the sealing bead to form a close portion of the support bead relative to the sealing bead. 
     
     
       12. A metal laminate gasket according to claim 11, wherein the metal gasket is a cylinder head gasket situated under a cylinder head with a rigidity, said close portion being located near the bolt hole when the rigidity is high where the cylinder head does not substantially bend when the engine is tightened. 
     
     
       13. A metal laminate gasket according to claim 12, wherein said sealing bead has a spring constant greater than that of the support bead. 
     
     
       14. A metal gasket according to claim 3, wherein said metal gasket is a cylinder head gasket situated under a cylinder head with a rigidity, said close portion being located at a portion away from the bolt hole when the rigidity is low where the cylinder head slightly bends when the engine is tightened. 
     
     
       15. A metal gasket according to claim 14, wherein said sealing means is a bead concentrically surrounding the fluid hole. 
     
     
       16. A metal laminate gasket according to claim 11, wherein said metal laminate gasket is a cylinder head gasket situated under a cylinder head with a rigidity, said close portion being located at a portion away from the bolt hole when the rigidity is low where the cylinder head slightly bends when the engine is tightened. 
     
     
       17. A metal laminate gasket according to claim 16, wherein said sealing bead has a spring constant greater than that of the support bead.